fglrx drivers freeze Xorg

Sometimes Xorg freeze, I can no more move the mouse or open a virtual TTY (ctrl-alt-Fn).
But I can access to a terminal by ssh and see Xorg process at 100%.
If I try to kill Xorg or Lightdm or gnome-session, that does nothing, my screen is still freezed, I can not kill Xorg.
All I can do is reboot the computer.
It's the Fourth time I have this bug and apport-gtk do not report it.
So I joined the result of a of dmesg command wich contains a dump result.

Thanks for your help.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: fglrx-updates 2:9.010-0ubuntu5
ProcVersionSignature: Ubuntu 3.8.0-8.17-generic 3.8.0
Uname: Linux 3.8.0-8-generic x86_64
NonfreeKernelModules: fglrx
.tmp.unity.support.test.0:

ApportVersion: 2.9-0ubuntu2
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom]
CompositorRunning: None
Date: Sat Mar 2 10:30:21 2013
DistUpgraded: 2013-02-13 03:05:04,175 DEBUG failed to SystemUnLock() (E:Non verrouillé)
DistroCodename: raring
DistroVariant: ubuntu
GraphicsCard:
 Advanced Micro Devices [AMD] nee ATI Pitcairn PRO [Radeon HD 7800] [1002:6819] (prog-if 00 [VGA controller])
   Subsystem: PC Partner Limited Device [174b:e218]
InstallationDate: Installed on 2012-07-07 (237 days ago)
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
JockeyStatus:
 kmod:fglrx - Video driver for the AMD graphics accelerators (Propriétaire, Désactivé, Non utilisé)
 kmod:fglrx_updates - ATI Fire GL (Propriétaire, Activé, Non utilisé)
MachineType: MSI MS-7752
MarkForUpload: True
PlymouthDebug: Error: [Errno 13] Permission non accordée: '/var/log/plymouth-debug.log'
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-8-generic root=UUID=0f08ee3a-4677-4c05-ab94-5d9805be3326 ro quiet splash vt.handoff=7
SourcePackage: fglrx-installer-updates
UpgradeStatus: Upgraded to raring on 2013-02-13 (17 days ago)
dmi.bios.date: 06/19/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V2.5
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: Z77A-G45 (MS-7752)
dmi.board.vendor: MSI
dmi.board.version: 1.0
dmi.chassis.asset.tag: To Be Filled By O.E.M.
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV2.5:bd06/19/2012:svnMSI:pnMS-7752:pvr1.0:rvnMSI:rnZ77A-G45(MS-7752):rvr1.0:cvnMSI:ct3:cvr1.0:
dmi.product.name: MS-7752
dmi.product.version: 1.0
dmi.sys.vendor: MSI
version.compiz: compiz 1:0.9.9~daily13.03.01-0ubuntu1
version.fglrx-installer: fglrx-installer N/A
version.ia32-libs: ia32-libs 20090808ubuntu36
version.libdrm2: libdrm2 2.4.42-0ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.0.2-0ubuntu1
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.0.2-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.13.2-0ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.1.0-0ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.21.3-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.6-0ubuntu3
xserver.bootTime: Sat Mar 2 10:10:54 2013
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.13.2-0ubuntu2
xserver.video_driver: fglrx